Key Laboratory of Humid Sub-tropical Eco-geographical Process of Ministry of Education, Fujian Normal University, Fuzhou, 350007, China; School of Geographical Sciences, Fujian Normal University, Fuzhou, 350007, China; Wetland Ecosystem Research Station of Minjiang Estuary, National Forestry and Grassland Administration, Fuzhou, 350215, China.
CSIC, Global Ecology Unit CREAF-CSIC-UAB, Bellaterra, 08193, Barcelona, Catalonia, Spain; CREAF, Cerdanyola del Vallès, 08193, Barcelona, Catalonia, Spain.
Chemosphere. 2023 Jan;311(Pt 1):137083. doi: 10.1016/j.chemosphere.2022.137083. Epub 2022 Nov 2.
Reclamation and conversion of wetlands strongly affect nutrient cycling and ecosystem functions, while little attention has been paid to the effects of converting coastal wetland to aquaculture on the cycling and balance of soil phosphorus (P). Herein, we investigated soil P fractions, alkaline phosphatase (ALP) activity, and associated microbial properties following coastal wetland conversion in subtropical China. Soil P availability (especially resin-P) concentration and ALP activity in wetland were significantly higher than those in pond. The conversion of coastal wetlands to aquaculture significantly reduced the abundance and diversity of bacterial phoD genes and altered their community structure. The lower phosphatase activity and associated microbial properties after wetland conversion suggested a weaker capacity of microbes to transform organic P (Po) to inorganic P (Pi), consistent with the low P availability but the high Po:Pi ratio in pond. Structural equation modeling indicated that the conversion of the wetland to the pond decreased ALP activity and P availability by affecting soil variables such as bulk density, pH, the carbon: nitrogen ratio, and/or moisture. It was concluded that wetland conversion to pond reduced soil P availability and phosphatase activity, altered the abundance, diversity and community composition of the phoD gene, and ultimately affected coastal P cycles and balances. Moreover, an extended corollary is that the smaller amounts of variation in soil total P and lower labile P concentrations in pond than in wetland suggest that large amounts of P (introduced in feed and not harvested in shrimp) are "lost" from the system. Thus, aquaculture ponds might serve as a source of P for the surrounding environment. More investigations focusing on the P biogeochemical cycle and its potential impacts on adjacent ocean environments at regional and global scales is urgently needed, which could contribute to better management of coastal land uses.
湿地的开垦和转化强烈影响养分循环和生态系统功能，而对于将沿海湿地转化为水产养殖对土壤磷（P）循环和平衡的影响，关注甚少。在此，我们调查了中国亚热带沿海湿地转化后土壤 P 组分、碱性磷酸酶（ALP）活性及相关微生物特性。湿地中土壤 P 有效性（尤其是树脂-P）浓度和 ALP 活性显著高于池塘。沿海湿地向水产养殖的转化显著降低了细菌 phoD 基因的丰度和多样性，并改变了它们的群落结构。湿地转化后磷酸酶活性和相关微生物特性较低表明微生物将有机磷（Po）转化为无机磷（Pi）的能力较弱，这与池塘中低 P 有效性但高 Po:Pi 比一致。结构方程模型表明，湿地转化为池塘通过影响土壤变量（如容重、pH 值、碳氮比和/或水分），降低了 ALP 活性和 P 有效性。结论是，湿地转化为池塘降低了土壤 P 有效性和磷酸酶活性，改变了 phoD 基因的丰度、多样性和群落组成，最终影响了沿海 P 循环和平衡。此外，一个延伸的推论是，池塘中土壤总 P 的变化较小且可利用 P 浓度较低，表明大量 P（来自饲料而不是虾类收获）从系统中“流失”。因此，水产养殖池塘可能成为周围环境的 P 源。迫切需要更多关注 P 生物地球化学循环及其对区域和全球尺度相邻海洋环境的潜在影响的研究，这将有助于更好地管理沿海土地利用。
